There were legends that Death was apparently conceived when the "gods" were drunk, (PROSE: Return of the Living Dad) being created from the dreams and thoughts of Time Lords, becoming personified into an "abstract universal entity." (PROSE: Human Nature)

Early in life, during the youth of his first incarnation, the Doctor killed Torvic. He made a deal with Death. Rather than having Death make him her champion, Death would choose another Time Lord, later known as the Master. However, the Doctor would later forget about this encounter. (AUDIO: Master)

The Doctor recalled seeing Death on a Gallifreyan hillside (presumably, before he knew who Death was). (PROSE: Set Piece)

When the Doctor suffered a one-sided heart attack at Roz Forrester's funeral, he had a vision of Death taunting him about taking the life of one of his companions, and that some day soon, she will take him, when he is alone and friendless, without warning and without meaning. (PROSE: So Vile a Sin)

At some point, the Doctor made a deal with Death, to give the Master a new start in life as a good and honest man for ten years, feeling guilty for how he turned out. However, after the ten years, it was agreed he would have to kill the Master.

When the ten years expired, Death sent the Doctor to Perfugium, where "John Smith" was living. Taking on the identity of John Smith's maid, Jade, Death tormented the Doctor, John Smith and his friends. This led to one of his friends, Victor Schaeffer, killing his own wife, and John's love, Jacqueline. When the Doctor couldn't go through with killing John, he realised his significance in creating the Master, and how he had turned him into Death's Champion, by making his original deal with Death.

He constructed a new deal with Death, so that he wouldn't have to kill John, but would instead have to kill an innocent person in the place of an assassin (who was just a disguise of Death again), but couldn't go through with that deal either. Death also made a deal with John Smith that to remain as John Smith, he had to decide whether he would make the Doctor Death's Champion, or if he would kill Victor so that Jacqueline would be reborn, but become the Master again. It is still unknown what his decision was. (AUDIO: Master)

Death stalked the Seventh Doctor for some time. The Doctor ended up making a deal with Death so that he could save the life of a tramp, unaware that his death would have had repercussions in the Web of Time. (PROSE: The Tramp's Story)

At one point, Death took the name "LaMort" and moved to Sydney in the 19th century, interested in the novelty of colonial Australia. Two hundred years later, she had become bored with all the ways and places that death took place. She intended to commit suicide. However, the Doctor, Benny, and Ace visited her, and the Doctor made Benny describe all the planets that humans had brought death to in her time. With the promise of all these new virgin worlds, Death resolved not to commit suicide, and she dropped her pills; they transformed into souls and melted away. (PROSE: Virgin Lands)